This invention relates to a printed and embossed material, suitable for use as a floor covering and a method and apparatus for making it in a continuous process. More particularly, it concerns a multilayered material combining a base layer, a preprinted vinyl layer and a wear resistant layer, which is embossed in register with the print.
Reverse printed laminates have been made by laminating separate sheets of calendared base material and a preprinted plastic film. Until recently, in continuous processes the printed designs have been limited to random prints because of the difficulty of maintaining the desired dimensions in the preprinted plastic film in the laminate and in some cases in the base material. The plastic film tends to stretch when it is being printed and subsequently dried. Since it is necessary to apply tension to the printed film during lamination in order to eliminate trapped air and wrinkles, the printed design can also be distorted during lamination.
Alternatively, tiles can be formed in batch processes with designs that are in register to the cut tile by laminating preprinted plastic sheets having silk screen designs to sheets of a suitable base material. The tiles can then be hand clicked from the sheets. The high cost of such a batch process makes in-register printed tile quite expensive and limits its acceptance.
An additional complication is imposed by the desirability of providing a textured surface by embossing the tile. Because the embossing step can be another cause of distortion, some processes are limited to embossing of a plastic surface layer that is integral with a nonplastic stable substrate such as asbestos or asphalt-saturated felt.
As described in U.S. Pat. Nos. 4,312,686, 4,612,074, and 4,773,959, and U.S. Pat. application Ser. No. 07/428,262, now U.S. Pat. No. 5,122,212 which are incorporated herein by reference, the distorations which occur during printing and laminating are minimized by printing the design on a stable base, preferably release paper, and then transferring the printed design to a hot plastic web made continuously by an extruder. This hot plastic web is made from a mixture of vinyl chloride or vinyl acetate copolymer, mineral filler such as limestone, and small quantities of other ingredients. Additionally, scrap material from previously formed floor tiles is ground and added to the mixture to conserve materials, reduce waste and lower costs. The resultant mixture is typically bleached with titanium oxide to lighten the color.
After printing, a stress relieved protective wear coat is laminated to the printed web. The laminated web is then embossed with an engraving roll which is aligned to the laminated web by means of registration marks formed as part of the printing on the web. Additionally, these marks align a cutting means with the web so that individual tiles can be cut automatically in register with the printed and embossed pattern. A carrier belt supports the hot plastic web during the printing stage, the laminating stage and the embossing stage to avoid distortion thereof.
Although the method described above is commercially successful, it produces tiles having somewhat subdued colors because the background portion of the tile is made from a hot plastic web formed partially from scrap tiles of varying colors. Thus, the background color is not white even after bleaching, and this background color can distort and dull the color of the printing on the tiles. Further, tiles manufactured to have the same color can be inconsistent with one another if they are printed on webs of varying colors. This inconsistency results in tile in which the colors are not completely reproducible.